OpenSolaris was introduced in June 2005 by Sun Microsystems. The OpenSolaris source code is also available online.
There is also a site for the Solaris Internals book.
Richard McDougall: a Distinguished Engineer at Sun Microsystems who specializes in operating systems technology and systems performance.
Jim Mauro: a Senior Staff Engineer in the Performance, Architecture, and Applications Engineering group at Sun Microsystems. His work focuses on "Solaris performance on Opteron platforms, specifically in the area of file system and raw disk IO performance." Interestingly he lives in New Jersey. Who knows I might bump into him one day (that would be very cool).